Bright New Resources for Syphilis Research: Genetically Encoded Fluorescent Tags forTreponema pallidumand Sf1Ep Cells

Abstract

SUMMARYThe recently discovered methodologies to cultivate and genetically manipulateTreponema pallidumsubsp.pallidum(T. pallidum) have significantly helped syphilis research, allowing thein vitroevaluation of antibiotic efficacy, performance of controlled studies to assess differential treponemal gene expression, and generation of loss-of-function mutants to evaluate the contribution of specific genetic loci toT. pallidumvirulence. Building on this progress, we engineered theT. pallidumSS14 strain to express a red-shifted Green Fluorescent Protein (GFP) and Sf1Ep cells to express mCherry and blue fluorescent protein (BFP) for enhanced visualization. These new resources improve microscopy- and cell sorting-based applications forT. pallidum, better capturing the physical interaction between the host and pathogen, among other possibilities. Continued efforts to develop and share new tools and resources are required to help our overall knowledge ofT. pallidumbiology and syphilis pathogenesis reach that of other bacterial pathogens, including spirochetes.Graphical abstractBy employing genetic engineering,T. pallidumwas modified to express GFP, and Sf1Ep cells to express mCherry on the cytoplasmic membrane and BFP in the nucleus. These new resources for syphilis research will facilitate experimental designs to better define the complex interplay betweenT. pallidumand the host during infection.